The Retreat at the Blue Lagoon – a low-slung, 62-suite escape that lurks half-hidden in the rugged landscape just outside Iceland’s capital, Reykjavik – has only been open for three months, and it is already one of the buzziest luxury spots in Europe. Perched on the edge of the geothermally heated pool for which it is named, it features floor-to-ceiling windows with spectacular views across the lava rock, plus a spa that offers in-lagoon massages. Guests get one especially attractive perk: after-hours access to the spectacular natural site, whose waters are packed with crowds during peak times.

But within the retreat lies one exclusive space that few visitors will ever know exists. Spread across two levels and 2,100 square feet, the Blue Lagoon suite is almost triple the size of any other. It has a private balcony overlooking the lava landscape, a kitchen and dining room, and a king-size bedroom with walk-in closet. Best of all, it has its own private spa, complete with a steam bath, sauna, fireplace, and a private bathing area within the lagoon.

The catch? The lavish suite costs US$10,500 per night, with a two-night minimum – and it is not listed on the hotel’s website. No photographs, no description, nothing at all.

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The Secret World of Unlisted Hotel Suites

The Blue Lagoon suite is like a cross between an unlisted phone number and a house seat at a theatre: You cannot find it unless you already know it is there, and booking is by invitation only. At high-end hotels around the world, these unlisted rooms are a subtle staple, with raisons d’être as varied as the rooms themselves.

According to Mar Masson, the hotel’s director of marketing, the Blue Lagoon suite is intended as the ultimate hideaway. For those who want to slip in unnoticed, a private entrance and nearby helipad allow discreet, private connections from Keflavik International Airport.

“No one ever needs to know you’re there,” he says. “It’s not visible to other guests, and there is nothing that indicates it is there.”

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Privacy is not the only reason to keep a room unlisted, whether on a hotel’s own site or on partners such as Sometimes it is about protecting your most valuable asset.

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“Let’s say you have a top suite that costs US$2,000,” says hospitality veteran Stephen Brandman, who runs management firm Journal Hotels. “You don’t want 10 people coming together and each throwing in US$200 so they can have a big party. Think about it. A load of high school prom students rent a penthouse, and all of a sudden you’ve got a big problem.”

New York University hospitality professor Bjorn Hanson agrees. “Rooms that have something fragile about them – the art, a Steinway grand piano – where there is too much risk of wear and tear will be held back,” he says. “They won’t be available to the public but assigned to VIPs.”

Often these types of rooms are referred to as “owner’s suites”. At the soon-to-open Hotel Bennett in Charleston, South Carolina, Michael Bennett’s one-bedroom, 2,000-square-foot suite is only available by special request. Even then, guests are only confirmed after a personal signoff from the developer himself.

At other properties, they are called “partnership rooms”, which means they are only available through exclusive membership clubs that require six-figure buy-ins. At Paradise Beach on the Caribbean island of Nevis, two of the resort’s new beach houses – which sit on stilts at the water’s edge – can only be rented via Exclusive Resorts, a vacation club whose initiation fee is US$125,000.

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By Invitation Only

Economically speaking, it may seem counterintuitive to keep your most expensive product shielded from public view. But hotels prefer not to shoulder the risk of a last-minute, fee-free cancellation on a pricey suite, and splurging travellers are more prone to last-minute pangs of guilt than a wealthy regular. For this reason, the JW Marriott Essex House in New York and San Francisco’s St. Regis require their penthouse suites to be booked via email – it gives managers time to vet potential stays before confirming a reservation.

Of course, there is also the perennial question asked by rejected walk-ins at hospitals and restaurants: “What would you do if Beyoncé dropped in?” At many hotels, a few luxury rooms are always kept empty in case a valued VIP decides to stay on a whim. These are not always celebrities; they can simply be big spenders. At the Cosmopolitan in Las Vegas, the 21 Boulevard penthouses are entirely unlisted, unbookable, and reserved for those who spend a cool million in the high-roller lounge.

Exceptions to the Rule

Unlisted rooms are not always the biggest or the most glamorous. Sometimes, they are botched or rejected prototypes for renovations that have hung around for financial reasons. And sometimes they are just unusually small or oddly shaped. According to travel industry analyst Henry Harteveldt of Atmosphere Research Group, these broom-closet-size rooms are most common in older, Grand Hotel-era properties, which were “built to serve people who travelled with staff, like a personal butler, a valet or a maid”.

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Harteveldt says while many of those cramped quarters have been knocked together or reconfigured, such renovations are not always possible, leading hoteliers to turn them into cheaper, secret rooms that are held in reserve. That is how New York’s Moxy Hotel in Times Square – which was built in 1907 as the Mills Hotel – ended up with its 120-square-foot Crashpad rooms. They are priced at just US$99 per night and are truly off-menu: They are only bookable off the drinks menu at the Magic Hour rooftop bar, for guests who have had one martini too many.

In other words: Don’t assume that all of your options are listed on a hotel’s website. And know that like any good secret, unlisted suites are always at risk of going public.

“Honestly, we might put [the Blue Lagoon suite] out there at some point,” says Masson, meaning listing it publicly, not talking to [Bloomberg] for this article. “But for now, we want it to be like a hidden gem.”

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